Audio mixers and consoles have long been staples in recording studios, live venues, and broadcasting applications as central stations for processing audio and producing a final product. With so many options, from super-simple entry-level portable mixers to extravagant multi-million-dollar studio desks, there certainly must be a difference in sound quality between mixers, right?
Do audio mixers affect audio/sound quality? Audio mixers, like any audio device, do affect the quality of audio signals passing through them. In addition to adjusting levels, panning, effects, and more, audio mixers inherently colour the audio via gain stages, A/D and D/A converters (digital mixers), and signal paths more generally.
In this article, we'll discuss audio mixers and the components of mixers that affect sound/audio quality to better understand how audio, and the components that make audio possible, work.
The Roles Of Mixers & Their Sound
Mixers used to be the protagonists of all things audio. From the Beatles to Pink Floyd, from single-channel to 64 and beyond, they were the key element to shape the audio for generations.
Nowadays, they are no longer necessary for making records. That being said, every mixer is a unique tone-shaping instrument that can and will colour your signal in a particular way.
Let's see this with an example. Dave Grohl (Nirvana, Foo Fighters, etc.) shot an entire movie called Sound City around a mixing console. In this clip, you can hear Dave talking about how and why he took Sound City's Neve console to Foo Fighter's studio.
But why spend a fortune to buy and take home an old, humongous artifact from the past? Well, the answer to that is because mixers do affect audio quality. In that sense, Dave says in the interview that the Neve console has a distinct “personality” and “sounds like no other board”. In other words, he is fascinated with the colour that the mixer adds to the sound passing through it.
Like Dave, anyone trying to get a little analog colour to their digital recordings can benefit from adding a good analog mixer to the setup in their studio. But let's dissect the anatomy of a mixing board so you can understand what “colours” the sound in such a delightful way.
What about the use of mixers outside the studio atmosphere? Well, the most common place you'll find mixers is at live events and shows. In this environment, mixers are still a fundamental piece of equipment you'll find in most venues.
As the name implies, an engineer utilizes the mixer to mix the sounds captured by microphones. So, the audio goes through the same pre-amplification stage, including equalizers and gain, which adds coloration to the signal. Thus, beyond the fact that mixers are needed to mix the sounds, they can (and will) add a particular vibe to the live sound as well.
Some newer models might even have an A/D converter to record the performance to a computer as a stereo track.
But mixers aren't only used in high-end recording studios or world-famous venues and broadcasting centres, for that matter. There are plenty of affordable mixers in home studios worldwide and compact mixers being lugged around by podcasters, journalists, and recording artists.
These mixers also have their own “sound,” though there likely aren't as many high-end components and processors as the big-name consoles.
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Audio Mixers Affect Audio Quality
All additional equipment an audio signal must flow through will have an effect on its sound. Analog audio is effective alternating current, which is subject to all the physical laws of electricity as it passes through the conductors or various audio components/devices.
Since mixers are generally made of multiple components, there will be multiple opportunities for the mixer to “colour” the signal. Even if the signal isn't audibly changed, it will, by default, be altered by the simple fact of passing through audio components.
Digital audio, which isn't as prone to noise/interference and other degradation, may not be subject to change as it is transferred through a digital mixer's signal path. However, the analog-digital and digital-analog converters required for recording and playing back analog audio will affect the audio signal.
So, although much of this “colouration” may not exactly be noticeable (though it certainly can be), there's no escaping the issue of audio being passed through the mixer.
Breaking a mixer down into smaller components, we have the following elements that could alter the audio signal quality:
As you might know, when plugging an instrument straight in or a dynamic or ribbon mic, the gain level it reaches the mix with is usually very low.
Thus, unless we are talking about active circuitry in the instrument or microphone, you have to push the levels in the mix, elevating the signal's noise floor and amplifying any unwanted noises.
A mixer can solve that with (usually) a single knob, the gain stage or preamplifier in every input. In other words, you can bring up the signal before it even makes it into the tape or computer. This means you won't have to manipulate its volume afterward, bringing unwanted noises to your pristine-clear mix.
Although you can get them separately, preamplifiers are the main reason for having a good mixer in your studio. In case you are not familiar with them, the pre-amplification stage is the moment in which the audio gets its initial processing, including equalization in most cases.
This means that the pre-amplification stage will imprint a distinctive coloration to the track.
Indeed, that might be the reason why good preamplifiers (Neve 1073, API 512 and 212, SSL, or Universal Audio 610, for example) are among the most sought-after pieces of equipment in the world of high-end audio. Moreover, they can make the difference between a stale-sounding vocal and a warm, articulate, dynamic take.
Although this is high-end gear found in elite studios, every pre-amplification stage colours the signal; thus, a good mixer will colour the sound more musically than a not-so-good model. In other words, the coloration depends on the mixer quality.
Cheaper preamplifiers will also affect the sound, though perhaps not as pleasingly. Low-end preamps may also introduce unwanted noise if driven too much.
Like many other once-solely-analogy technologies, mixers have entered the digital age. Most audio retailers will carry digital mixers from a variety of brands.
These mixers are technically a blend of technology (analog and digital), which happens entirely inside the mixer.
Furthermore, many of these consoles or mixers blend in perfectly with your favourite DAW, and you can control what happens in the computer using buttons and knobs.
To achieve such a blend of analog and digital audio, mixers must have converters to alter audio signals from analog to digital and vice versa. These converters, named aptly, are known as analog-digital converters (ADCs) and digital-analog converters (DACs), respectively.
Digital mixers have analog-digital converters. This is because the information coming from microphones and instruments is analog, and thus, a digital system can't read it.
In case you are not familiar with them, A/D converters take the analog signal curve and copy (sample) it as close as possible using zeros and ones so that the computer can read it.
Digital audio is sampled a set number of times per second, depending on the sample rate. Common sample rates include 44.1 kHz, 48 kHz, 88.2 kHz and 96 kHz.
The amplitude of each sample will be defined as a specific value within a discrete set of values from no level (-∞ dBFS) to maximum level (0 dBFS). The bit-depth defines the number of possible amplitudes. Common bit-depths include 16-bit (65,536 possible amplitude values) and 24-bit (16,777,216 possible amplitude values).
Depending on the converter's resolution, it will use a specific number of zeros and ones in reconstructing the original, continuous analog waveform. Thus, the higher the bitrate, the closer to the original the resulting curve will be, and the higher the resulting sound quality (camera pixels and image quality work similarly).
What happens when you want to hear back the sound you've recorded (or are recording) through speakers and headphones? These devices don't read the binary language (zeros and ones); hence, you need to feed them an analog signal by converting the mixer's digital audio back to analog.
Digital to analog converters (D/A) are complementary to the A/D converters and are placed in another spot of the sound chain. Usually, digital mixers are built with A/D converters for audio going in and D/A converters for audio going out.
Again, the better the converters are, the more accurate the resulting sound quality will be. This counts for audio going in and out. So, check on your digital mixer what the bitrate is before buying.
Effects are a very common feature in boards concerned with music, in both live and studio environments. It's common for recording engineers to go for effects and processing after the sound is recorded to have more control. Live sound engineers are in a different situation because effects have to go in before the sound hits the speakers.
Thus, many live-oriented mixers (digital or analog) will include effects mostly related to vocals, such as reverb, delay, and compression. In the right hands, these can make a difference and enhance the performance of any live act.
Effects and processes are designed specifically to affect/manipulate the sound quality of the audio. As mentioned, common effects and processes include:
Compression: Dynamic range compression is the process of reducing the dynamic range of an audio signal (the difference in amplitude between the highest and lowest points). Compression does so by attenuating the signal amplitude above a set threshold point.
To learn more about compression, check out my article The Complete Guide To Audio Compression & Compressors.
Equalization: EQ is the process of adjusting the balance between frequencies within an audio signal. This process increases or decreases the relative amplitudes of some frequency bands compared to other bands with filters, boosts and cuts. EQ is used in mixing, tone shaping, crossovers, feedback control and more.
To learn more about EQ, check out my article The Complete Guide To Audio Equalization & EQ Hardware/Software.
Delay: Delay is a time-based effect where an input signal is recorded for a relatively short amount of time and is played back after a set period of time after the initial recording. There are many ways to achieve delay and different styles/types of the effect.
Reverb: The reverb effect recreates the natural effect of Reverberation, which happens when a sound wave hits a surface (or multiple surfaces). It reflects back to the listener at varying times and amplitudes. This creates a complex echo that holds information about the physical space.
Buying the best audio mixer for your specific applications (studio, field recording, live sound, broadcasting) can be rather complicated. For this reason, I've created My New Microphone's Comprehensive Audio Mixer Buyer's Guide. Check it out for help choosing the top audio mixer for your goals.